1. Field of the Invention
The present invention relates to a set of an ink and a reaction liquid, and an image forming method.
2. Description of the Related Art
In recent years, an ink jet recording method has been required to achieve both adaptation to high speed recording and acquisition of an excellent optical density on a recording medium, in particular, plain paper, at a high level. In order to meet this requirement, in the ink jet recording method, there has been variously proposed a process in which a liquid for making an image good is provided as what is called a reaction liquid separately from an ink containing a coloring material, and the reaction liquid and the ink are applied to a recording medium to form an image.
For example, there has been a proposal for controlling an ink and a reaction liquid so as to slow the speeds of penetration and diffusion thereof into a recording medium, not by improving the reactivity between them, thereby achieving a high optical density (see Japanese Patent Application Laid-Open No. 2008-308663). Specifically, a reaction liquid whose dynamic surface tension at a lifetime of 30 milliseconds is 41 mN/m or more and an ink whose static surface tension is high to some extent are used, thereby ensuring a time period during which a coloring material aggregates on the surface of the recording medium to improve the optical density. On the other hand, in order to solve a problem of clogging caused by an aggregate produced by a reaction in an absorber within a cap protecting a recording head or in a waste liquid absorber of a recording apparatus, there has been a proposal for inhibiting a reaction at a position where it is not wanted to cause the reaction (see Japanese Patent Application Laid-Open No. 2008-155520). Specifically, it has been proposed to provide an ink containing a reaction inhibitor for inhibiting such a reaction separately from the reaction liquid and the ink.